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Fair Value Measurement (Detail Textuals) - shares
1 Months Ended 12 Months Ended
Sep. 29, 2018
Dec. 31, 2018
Dec. 31, 2017
Pre-IPO Series C-2 convertible redeemable preferred shares      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Issuance of preferred shares 483,702 483,702 0